An experimental and theoretical high temperature kinetic study of the thermal unimolecular dissociation of fluoroethane.
The thermal dissociation of fluoroethane has been studied using shock tube (ST)/time-of-flight mass spectrometry (TOF-MS) at 500 and 1200 Torr over the temperature range 1200-1550 K. The ST/TOF-MS experiments confirm that elimination of HF is the only reaction channel and rate coefficients for this reaction were extracted from concentration/time profiles derived from the mass spectra. Results from a novel diaphragmless shock tube coupled to the TOF-MS are also presented and demonstrate the unique ability of this apparatus to generate sufficiently reproducible shock waves that signal averaging can be performed over multiple experiments; something that is not possible with a conventional shock tube. The dissociation is also studied with ab initio transition state theory based master equation simulations. A modest increase in the calculated barrier height (i.e., by 1 kcal mol(-1)) yields predicted high pressure rate coefficients that are in good agreement with the existing literature data. The present pressure dependent observations are accurately reproduced for a downwards energy transfer for neon at 1200 to 1500 K of approximately 270 cm(-1), which is somewhat smaller than that found in previous studies on fluorinated ethanes with the same bath gases.
Giri
Binod R
BR
Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4831, USA. tranter@anl.gov
Kiefer
John H
JH
Xu
Hui
H
Klippenstein
Stephen J
SJ
Tranter
Robert S
RS
D004867:Equipment Design; D004980:Ethane / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D006858:Hydrofluoric Acid / Q000737:chemistry / Q000302:isolation & purification; D007700:Kinetics; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods; D008956:Models, Chemical; D011312:Pressure; D011789:Quantum Theory; D013816:Thermodynamics
D006845:Hydrocarbons, Fluorinated; D005461:Fluorine; D004980:Ethane; D006858:Hydrofluoric Acid